Pi-based Domestic Electricity Monitor - Part 1

I want to try and use my Pi for some kind of home energy control and monitoring use.

I thought of a few options, including controlling my infra-red heaters. That was probably a bit ambitious for a first project, but it did lead to me controlling my Christmas tree lights with my Pi and a relay board - both in Python and Scratch GPIO.

I noticed my electricity meter has a red LED that flashes periodically at intervals that depend on the rate of consumption, and thought about using a light-sensor-enabled Pi to monitor the electricity used. Turns out this has been done before. Lots of times...

http://www.hyggeit.dk/2013/04/super-cheap-web-enabled-power.html

http://jonarcher.info/2014/03/arduino-based-electricity-monitor/

http://openenergymonitor.org/emon/node/2017

http://www.reuk.co.uk/Flashing-LED-on-Electricity-Meter.htm

I've got as far as building the sensing circuit on a breadboard, ready to start learning the code I need to make it work. I'm looking forward to the maths!

Ultimately, I'm thinking the data will write to an SQL database that can be read and posted to a web page in real-time, possibly with a graph too.